Sailing vessels have long been employed by man as a mode of transportation. Centuries ago sailing vessels, such as a clipper ships, played an instrumental role in man's exploration of new territories and the transportation of goods between these territories. Over the years these sailing vessels have evolved to take on a variety of forms.
Some of these crafts, such as the yacht and the windsurfer or sailboard, are used both recreationally and in competitive sporting events throughout the world. Windsurfing is a recently evolved form of sailing in which a flexible sail that is free to rotate about a mast assembly is mounted onto a surfboard and the craft is guided by a standing rider. Although the craft has a unique design compared to those of larger sailing vessels, the mechanics of operation are quite similar, with the primary goal being to utilize the force of the wind to navigate the craft along a desired course. Navigational versatility is achieved with a triangular sail that can be rotated about the craft's mast assembly to engage the wind at various angles so that the sail serves to propel the craft at any angle to the wind, except head-on.
Modern day windsurfing boards are relatively simple crafts which structurally include a hull with a sail on a tilting mast and a small keel therebeneath. The operator grasps a wishbone boom that is attached to the mast assembly to move the sail in any direction in order to take advantage of the wind. Accordingly, the sail not only drives the windsurfer forward but also steers it.
While the mechanics of operating a windsurfing boards are straightforward and embody the same principals utilized on other sailing vessels, these mechanics are very difficult to master without a great deal of practice. For example, when sailing with the wind directly behind the windsurfer's back, the sail is held at right angles to the wind to propel the craft forward. When sailing into the wind, it is necessary that the sail be held edge-on to the wind so that the wind blows it around. The wind then inflates the sail and curves it so that the sail becomes an air foil. The directional air flow produces a suction force that would pull the sail at right angles to the wind if not for the operator's resistance. Instead, the windsurfer moves forwardly at an angular direction relative to the wind and progresses into the wind in an indirect way by "tacking" or following a zig-zag course. In order to sail crosswise to the wind, the sail is still positioned at right angles to the wind. Here, however, water resistance on the keel of the hull operates to resist movement of the craft in the direction of the wind thereby propelling the craft transversely to the wind's direction.
The sail of a conventional sailboard has its luff edge formed as a sleeve through which a flexible mast pole is slideably received. Typically, the head of the sail is secured to a distal end of the mast post, while the sail's tack is connected at the base of the mast assembly by a tether line. As such, the sail's luff edge is held in tension between the head and the tack. It is typical to the proper operation of a sailboard that this downhaul tension be maintained in a range of four hundred (400) to six hundred pounds (600 lbs) of force.
It is not uncommon during navigation of a sailboard that the downhaul tension needs to be changed due to changes in wind conditions, for example, wind velocity. In such case, it is necessary to increase or decrease the tension on the tether line which is often under a tension force that is as much as two hundred pounds (200 lbs) acting through a pulley system. This, of course, can be exceedingly difficult for almost anyone, and particularly individuals of less stature. Without some ability to change the effective length of the mast assembly, however, there is sometimes not enough adjustment capability to compensate for such condition. Moreover, this adjustment method causes a change in the center of effort, i.e., the center of force of the wind on the sail relative to the hull. This change causes the torque on the craft to correspondingly change, resulting in alteration of the craft's maneuverability and control.
In the past it has been known to employ a mast assembly having a pole support interposed between the flexible mast pole which receives the sail and the mast foot which is connected to a sailboard in an effort to alleviate this problem. As discussed more thoroughly below in reference to FIGS. 1-3, the pole support of these prior known mast assemblies is telescopically received within the flexible mast pole. The mast pole is supported by a collar which extends around the pole support and this collar is manually positionable at selected discrete locations along the pole support. Accordingly, the effective length of the mast assembly can be changed, and the tension reapplied by the tether and pulley system in order to increase or decrease downhaul tension on the luff edge of the sail.
While this known construction for a mast assembly is advantageous because it provides an alternative approach to adjusting tension on the sail, the manual adjustability of the effective length of the mast assembly can be quite cumbersome. In addition, this type of device has a drawback in that it only permits a limited range of adjustability for the sail's tension. Adjustment is often difficult while the sailcraft is being used since this structure requires removal of the sail tension in order to change the mast assembly length. Accordingly, there remains a need to provide a pole support for use in the mast assembly of a sailing craft which is selectively operable to facilitate adjustability of a sail's tension throughout a broad range of adjustment positions. The present invention is directed to meeting this need, among others.